Enhancing the photodegradation activity of n-type WO3·0.33H2O by proton-intercalation via negative potential biases

Abstract

It is here demonstrated that proton-intercalation via negative potential biases enhance the rate constant of methylene blue (MB) photo-electrocatalytic de-colorization on n-type tungsten trioxide hydrate (WO3·0.33H2O as prepared by hydrothermal synthesis), rather than the positive potential bias in promoting the charge separation of photo-generated electrons/holes. Due to the generation of W(V) and W(IV) hydroxyl species with smaller band gaps (in comparison with W(VI)) and the electrochemical activation of WO3·0.33H2O, negatively biased proton intercalation into WO3·0.33H2O clearly enhances its photo-electrocatalytic activity for MB de-colorization, including its visible-light photo-electrocatalytic activity. A possible scheme for promoting the photocatalytic activity of WO3·0.33H2O through proton intercalation under constant potential biases is proposed and discussed. The photocatalytic de-colorization rate of MB on UV100-TiO2 is significantly decreased under the same potential biases due to the difficulty in proton-intercalation. © 2013 Elsevier B.V.